With the proliferation of wireless communications systems, compatible handheld communication devices are becoming more prevalent, as well as advanced. Whereas in the past such handheld communication devices were typically limited to either voice transmission (cell phones) or text transmission (pagers and PDAs), today's consumer often demands a multifunctional device capable of performing both types of transmissions, including even sending and receiving e-mail. Furthermore, these higher-performance devices can also be capable of sending and receiving other types of data including that which allows the viewing and use of Internet websites. These higher level functionalities necessarily require greater user interaction with the devices through included user interfaces (UIs) which may have originally been designed to accommodate making and receiving telephone calls and sending messages over a related Short Messaging Service (SMS). As might be expected, suppliers of such mobile communication devices and the related service providers are anxious to meet these customer requirements, but the demands of these more advanced functionalities have in many circumstances rendered the traditional user interfaces unsatisfactory, a situation that has caused designers to have to improve the UIs through which users input information and control these sophisticated operations.
For many reasons, screen icons are often utilized in such handheld communication devices as a way to allow users to make feature and/or function selections. Among other reasons, users are accustomed to such icon representations for function selection. A prime example is the personal computer “desktop” presented by Microsoft's Windows® operating system. Because of the penetration of such programs into the user markets, most electronics users are familiar with what has basically become a convention of icon-based functionality selections. Even with many icons presented on a personal computer's “desktop”, however, user navigation and selection among the different icons is easily accomplished utilizing a conventional mouse and employing the point-and-click methodology. The absence of such a mouse from these handheld wireless communication devices, however, has necessitated that mouse substitutes be developed for navigational purposes. Mouse-type functionalities are needed for navigating and selecting screen icons, for navigating and selecting menu choices in “drop down” type menus, and also for just moving a “pointer” type cursor across the display screen.
Today, mouse substitutes in handheld wireless communication devices take the form of rotatable thumb wheels, joysticks, touchpads, four-way cursors, and the like. In the present description, a trackball is also disclosed as a screen navigational tool. It is known to provide navigation tools such as the rotatable thumb wheel with a mechanically created ratchet-feeling effect that provides the user tactile feedback when rotating the navigation tool. This feedback provides the user with additional sensory information besides the induced visible motion on the display screen. In typical trackball assemblies, however, the trackball freely rotates within a receiving socket. Therefore, because of the many different directions within which freedom of movement is possible with a trackball, it is much more difficult to effect in a trackball a ratchet feeling similar to that provided in a thumb wheel, which rotates about a single fixed axis. The benefit of such ratchet-type, incremental feedback is, however, still desired for trackball implementations.